A rule induction framework for the determination of representative learning design in skilled performance

Representative learning design provides a framework for the extent to which practice simulates key elements of a performance setting. Improving both the measurement and analysis of representative learning design would allow for the refinement of sports training environments that seek to replicate competition conditions and provide additional context to the evaluation of athlete performance. Using rule induction, this study aimed to develop working models for the determination of high frequency, representative events in Australian Rules football kicking. A sample of 9005 kicks from the 2015 Australian Football League season were categorised and analysed according to the following constraints: type of pressure, kick distance, possession source, time in possession, velocity and kick target. The Apriori algorithm was used to develop two models. The first consisted of 10 rules containing the most commonly occurring constraint sets occurring during the kick in AF, with support values ranging from 0.15 to 0.22. None of the rules contained more than three constraints and confidence values ranged from 0.63 to 0.84. The second model considered ineffective and effective kick outcomes and displayed 70% classification accuracy. This research provides a measurement approach to determine the degree of representativeness of sports practice and is directly applicable to various team sports.     

Separability in a class of coordinate systems

A study is made of separability conditions for the Helmholtz and Laplace equations. Attention is confined to the most useful case for physical applications; namely,

1.

(a) The coordinate system is either cylindrical or it has rotational symmetry, and     

Simplified interflection calculations

The purpose of the paper has been to present simplified methods that will expedite the calculation of ceiling lighting (Type II). Approximate formulas have been given, which allow ordinary slide-rule calculations to be made very easily for the usual range of variables. Only with rooms having very high domance (or perhaps with extraordinarily high floor reflectance) are the complicated equations of the previous paper (1) needed. These approximate formulas can be represented also by alignment charts, Figs. 2 to 5, which further simplify the work.Either the formulas or the charts may be used to investigate the effect of a change in ?₁, ?₂, or ?₃. However, if reflectances are standardized at recommended values, other methods are possible.In particular, one may use graphs (Fig. 6) or a slide-rule (Figs. 7 and 8). The method of calculation chosen for a specific problem will depend on the problem and on the preferences of the designer. The previous equations and tables (3) may always be used; but in most cases, time can be saved by employing the short-cuts given in the present paper.     

Interflectance calculations for various luminaires

Previous interflectance tables have dealt principally with three basic types of lighting (Types I, II, and III). The present paper extends the scope of the interflection method by showing how it can be applied to rooms lighted by hanging luminaires. It is found that most cases arising in practice can be covered by six canonic distributions. The effect of mounting height is handled by means of a simple equation.     

Cultured pearls—commercialised biomineralisation

At the turn of the last century there was an ever increasing world demand for pearls while at the same time their known fishing grounds were becoming exhausted. Some way of artificially increasing their production was obviously desirable, and the problem attracted considerable effort. It was an attempt to exploit a scientifically poorly understood phenomenon, and it is interesting, in retrospect, to relate these attempts to recent concepts of biomineralisation. Pearls are, of course, the layers of aragonitic calcium carbonate secreted by molluscs.     

Radiant flux through apertures—I

Equations for the calculation of radiant power F through two apertures in series are well known. A characteristic of these formulae is that they give F as a small difference between two large terms. Evidently, the flux through the apertures must decrease as the spacing between them increases; and for large spacing, the inverse-square relation must hold. Instead of exhibiting this behaviour in an obvious manner, however, the traditional equations give the specious impression of an increase in F with increase in spacing. The paper develops an approximate formulae that applies to apertures in the shape of any regular polygon and that shows clearly how the inverse square relation is approached for large separation.